Blog 6: More Mr. Park Physics - Momentum

Once again, Mr. Park gives me new reasons to blog about physics. This time, I have decided to elaborate on the physics of his tennis prowess. 

Physics seems to follow him wherever he goes.

Every quarter, Mr. Park allows his Pre-Calculus Honors classes to challenge him at tennis. The rules are as follows:


1. If a student plays tennis, the game will be 1 v 1. If a student does not play tennis, then an unlimited number of students are allowed on the court against Mr. Park.
2. If the students do not play tennis, they receive a 30-love advantage over Mr. Park and can serve anywhere in the court boundaries. 
3. For every game won against Mr. Park, all PCH students receive one bonus point for the quarter.


Last quarter the students played Mr. Park for about four hours in total, and earned a total of 5 bonus points. Therefore we won one game (and thus one point) every 48 minutes spent in the hot sun. That is a really long time to spend just to earn one point. This means that Mr. Park is very good at tennis.


The reason? His serve. No mere student is capable of returning it. Why?


Let's take a look at the physics of his serve.
When Mr. Park serves the ball, the ball gains momentum. The more momentum that the ball has, the harder it is to stop the ball (and send it back).
On average, a tennis ball weighs about 0.057 kg and professional players (like Mr. Park) can serve the ball at 70 m/s. 
Thus, given p=mv, p=(0.057)(70)=3.99 kgm/s.
For comparison, a baseball pitch coming in at around 75 mph (high school pitchers) has about p=(.15)(33.5)=5.03 kgm/s of momentum. This means that returning Mr. Park's serve is actually somewhat comparable to hitting a baseball, except you don't know where the ball will land, and how deep it will land, or whether or not Mr. Park put a ton of spin on the ball. 


So that is why we cannot earn many bonus points in PCH, and that is why I cannot earn an A.

Not because we suck at tennis or anything.

Not because I suck at math or anything.

Blog 5: Physics of "Rocky"

After an exciting Homecoming week, I am finally ready to settle back into the fascinating world of physics. Looking back on Homecoming week, though, I can make many connections to physics, even after the rowdiest of celebrations. Here in this video, the ever-entertaining Mr. Park rocks out to the "Rocky" theme song:

Today's lesson in Pre-Calculus Honors: How to be awesome.

Hearing that spirited song now immediately conjures the image of Rocky Balboa climbing those 72 steps of the Philadelphia Museum of Art in intense training. However, I now understand the physics behind Rocky's training, and why it was so impressive.

After watching his ascent again, I estimate the time it took for him to climb those steps to be a little less than 7 seconds. With such a small time, sprinting with great acceleration (he had the entire city chasing after him) over a long and high distance, and a relatively large mass (probably about 100 kg), his power would be very high given the equation P= W/t = [(ma)(∆x)/t]. With such power, no wonder Rocky was so successful.

Go Rocky!

(Thanks to Mr. Park for the inspiration.)